The invention relates to an electronically controlled pneumatic fastener driving tool, and more particularly to such a tool having an improved electronic control system, an improved battery powered, solenoid actuated, remote valve, and a generator for partially recharging the solenoid battery each cycle of the tool.
Many types of pneumatic fastener driving tools are well-known in the art. Those most frequently encountered have a manual trigger and a safety, both of which must be actuated in order to cycle the tool. A workpiece responsive trip is the most usual form of safety. When the trip is pressed against the workpiece, it enables the manual trigger. When the manual trigger is actuated, the tool will cycle. An exemplary tool with a manual trigger and a safety of this type is taught in U.S. Pat. No. 3,278,106.
An xe2x80x9cAuto-Firexe2x80x9d mode of operation has heretofore been developed wherein the operator can drive a plurality of fasteners by simply pulling the trigger and moving the fastener driving tool along the workpiece. An example of such a tool is taught in U.S. Pat. No. 3,278,104.
The pneumatic fastener driving art has achieved a high degree of sophistication. It has been found that the more sophisticated pneumatic fastener driving tools have become, the more complex and the more expensive they are.
U.S. Pat. No. 4,679,719, incorporated herein by reference, teaches that if a pneumatic fastener driving tool is provided with an electronic control system, it could be greatly simplified in construction, eliminating complex valving and mechanical linkages. This reference further teaches that a pneumatic fastener driving tool having an electronic control system is more reliable, less expensive to manufacture and more versatile. The control circuit may have a number of input signals, in addition to those provided by the trigger and the trip from various additional devices associated with the tool and indicating various states or conditions of the tool. Finally, the control circuit may be pre-programmed to establish a desired mode of operation of the tool. The control circuit may be so designed that the operator can select one of a number of modes of operation by replacing one control circuit (in the form of a chip or the like) with another. Alternatively, the reference teaches that the control circuit could be pre-programmed in such a way as to enable the operator to select one of a number of modes of operation, by means of a mode selection switch. In any mode of operation, the control circuit interprets the inputs, including their presence or absence and their sequence. When the inputs satisfy the desired mode of operation, the control circuit will generate an output signal to the solenoid controlled remote valve, causing the tool to cycle. The reference finally indicates that the circuit could be so designed as to prevent cycling of the tool if the safety and trigger are not both activated within a predetermined time limit.
The present invention sets forth improvements upon the teachings of U.S. Pat. No. 4,679,719. The present invention teaches an improved electronic control system package mountable directly upon a pneumatic fastener driving tool. The package incorporates reed switches in the inputs from the manual trigger and the safety trip which are actuated by the manual trigger and safety trip, respectively. The tool of the present invention is provided with a solenoid actuated remote valve of novel design and powered by a rechargeable battery having an extended life by virtue of a generator incorporated in the tool in such way as to partially recharge the solenoid battery during each cycle of the tool.
According to the invention there is provided an electronically controlled pneumatic fastener driving tool. The tool is characterized by a body containing a cylinder with a piston/driver assembly therein. A main valve normally closes the top of the cylinder and is actuable to an open position introducing high pressure air into the cylinder to cycle the piston/driver assembly. The fastener driving tool is provided with a magazine supplying fasteners to be driven by the piston/driver assembly, a manual trigger, and a safety trip.
There is an electronic control system associated directly with the tool and comprising a remote solenoid valve to actuate the main valve, a microprocessor having inputs from at least the trigger and the safety trip, and an output to energize the solenoid of the remote valve to cycle the tool. A first battery is provided to energize the microprocessor and a second rechargeable battery is provided to energize the solenoid of the remote valve. A generator is associated with the tool to partially recharge the solenoid battery during each cycle of the tool.
The microprocessor is preprogrammed to determine the mode of operation of the tool. The microprocessor may be so designed as to provide two or more modes of operation for the tool, selectable by the operator through the agency of a mode selection switch, or by other means set forth hereafter.
The input from the manual trigger is enabled by a reed switch closable by the manual trigger, itself. Similarly, the input from the safety trip is enabled by a reed switch closable by the safety trip. The microprocessor may also be preprogrammed to provide a timer to impose a time limit with respect to the trigger, the safety trip, or both.